Tuberculosis (TB) remains a major health problem throughout the world. According to World Health Organization (WHO) data, although the number of annual cases has been falling since 2002, in 2010 there were 8.8 million incidental cases of TB, causing 1.4 million deaths worldwide.1

This decrease in annual cases has also been observed in Europe and Spain. According to data from the Spanish National Epidemiological Surveillance Network (RENAVE), the incidence rate for TB in Spain in 2010 was 15.5 cases per 100000 population, 8.4% lower than 2009 and 8% lower than 2008.2 This decrease occurred at the expense of pulmonary TB in particular, with the incidence rates of tuberculous meningitis and other TBs remaining stable. The TB rates declared to RENAVE are highly variable in each region, ranging between 8 and 29 cases per 100000 population, with the regions of Galicia, Melilla, and Cantabria having the highest overall rates. However, the information collected by RENAVE is incomplete with respect to certain important data, such as the presence of coinfection with human immunodeficiency virus (HIV) or treatment completion, and there is no information on other comorbidities in patients, different diagnostic microbiology tests or drug-resistance. Series published in recent years in Spain provide insight into important data with respect to treatment adherence and death rate.3,4 The percentage of those born outside Spain remains stable, around 30% of cases, and there appear to be differences between the native and immigrant populations with respect to age, adherence and anti-tuberculosis drug resistance.5–7 In the Balearic Islands, the TB incidence rate declared in 2010 was 13.3 cases per 100000 population, following the same downward trend described in the rest of the country.

The aim of this study was to describe the experience of a multidisciplinary single-specialty TB unit in Hospital Son Llàtzer (HSLL) (Palma de Mallorca, Spain), with emphasis on the time trend and 2 special populations – HIV-infected patients and immigrant patients.

Tuberculous disease is increasingly prevalent in our healthcare area, and is occurring in both the native and, to a larger extent, the immigrant population. Anti-tuberculosis drug resistance was very rare, and we only had 4 cases of multi-resistance during the period studied. The rates of drop-out and TB-related deaths were low.

Our data contrast with those of RENAVE and series published in Spain,2,11 which indicate that the incidence of TB has been falling in recent years. This rise in the number of cases in our area could have various explanations. The existence of a single-specialty, multidisciplinary TB clinic in our hospital and the teaching activities carried out around it may have raised awareness in clinicians to actively search for TB; furthermore, a study of contacts of patients diagnosed with TB in our hospital has been carried out since 2006, which has allowed a further 23 cases of tuberculosis to be diagnosed, i.e., 3.1% of the 741 contacts of the cases studied. This proportion of patients among the contacts of an index case is more than twice that observed in a study conducted in Vizcaya (Spain),12 and shows the importance of performing a systematic study of contacts of each TB case. Furthermore, the HSLL healthcare area covers economically deprived areas of the city with a high immigrant population, where there is probably a higher incidence of TB cases.

The proportion of HIV-coinfected TB patients was 11% and remained stable in the study period, although it was somewhat higher than that observed in other series and in data collected in the RENAVE or the European TB surveillance network,2,13 where HIV infection is described in 6% of cases. Other Spanish studies have shown a gradual decrease in the number of HIV-infected TB patients in recent years,5,10 which we did not observe in this small series. Substance abuse, especially smoking and intravenous drug addiction were more common in this group. Lung involvement was significantly less common than in patients not infected with HIV, unlike the disseminated forms, including meningitis, which were more common in this group, in agreement with the data declared in the country as a whole in this population.2 The high percentage of patients diagnosed simultaneously with HIV and TB in our study was notable.

The increase in the number of annual cases of TB occurs especially (although not exclusively) in relation to the immigrant population, as has already been observed in other studies.14 The overall percentage of immigrants in our series was 39.8%, higher than the 33% declared to RENAVE in Spain in 2010,2 and also higher than the 29.7% observed in the Spanish multicentre ECUTTE study.3 The countries of origin of most immigrant patients with TB in our area were Bolivia, Senegal and Nigeria, although immigration from these countries, according to 2011 data from the Palma municipal observatory,15 only constitutes a small proportion of the total immigration in Palma de Mallorca (5.4%, 2%, and 3.1%, respectively). As in other studies, the immigrant population tended to be younger, with less substance abuse and fewer comorbidities than the non-immigrant population.3,6 However, unlike the ECUTTE multicentre study,3 and the study conducted in Granada (Spain) by Molina-Rueda et al.,5 we did not observe poorer treatment adherence in the group of foreign patients, a higher death rate or a higher number of resistances to first-line anti-tuberculosis drugs as found in other Spanish publications.5,6

Most patients received 4 first-line drugs (RHZE) as the initial treatment for TB; the percentage of patients receiving this therapeutic regimen was higher in the immigrant population and in the case of TB recurrence, following national recommendations.16 However, in our area, we observed a low overall rate of resistance to isoniazid or to isoniazid/rifampicin (21 of 357 cases [5.9%], of which 4 were cases of recurrence). If we exclude the cases of recurrence, the percentage of primary resistance in our area is lower (4.2%) and we could even reconsider the need for initial treatment with 4 drugs in our area in some cases, as other authors have suggested.17

The death rate was low in our series, compared with others such as that published in 2006 by Pina et al.,18 where a death rate of 6.4% was observed, without specifying the underlying causes. Among European countries that also report death rates, the overall death rates published are higher (10.2%).12 In our series, the only variable associated with a higher risk of mortality was age, as has been published in other studies18,19; the death rates in patients with HIV were also significantly lower than those found in a large series in Catalonia (Spain) which showed, in the era of highly active ART, a death rate of 43.1% in HIV patients coinfected with TB.20 However, alcoholism, multi-resistance or the coexistence of a neoplasm were not associated with an increase in TB-related deaths. The low prevalence of patients with diseases such as diabetes or neoplasms, as well as multi-resistance, may explain this finding.

Unfortunately our study has certain limitations, primarily that this is a descriptive study with a retrospective nature. Furthermore, some of the sub-groups studied, such as HIV-infected patients, have a small number of cases. Another limitation, when estimating the possible role of the single-specialty unit, is that we do not have a period before its introduction to compare results. However, given that the migratory flow to Mallorca is relatively low, according to data from the Spanish National Statistics Institute,21 it seems unlikely to have influenced our results.

In our study, we observed an upward trend in the number of cases during the study period, as well as a higher percentage of immigrants than in other series and registers in Spain. Treatment adherence was similar in the immigrant and native populations, with low overall mortality. The index case contact study allowed us to diagnose a not inconsiderable number of cases. All of this reaffirms the importance of a single-specialty unit dedicated to the diagnosis and treatment of TB, and the study of contacts to optimize control of the tuberculosis endemic. We therefore consider that the financial difficulties experienced by the Spanish National Health System should not affect TB diagnosis and treatment programs, which are essential for achieving real control of the epidemic.

The authors declare that they have no conflict of interests.